Background

Recent studies have reported associations between particulate air pollution and daily mortality rates.

Population-based, cross-sectional studies of metropolitan areas in the United States have also found associations between particulate air pollution and annual mortality rates, but these studies have been criticized, in part because they did not directly control for cigarette smoking and other health risks.

Methods

In this prospective cohort study, we estimated the effects of air pollution on mortality, while controlling for individual risk factors.

Survival analysis, including Cox proportional-hazards regression modeling, was conducted with data from a 14-to-16-year mortality follow-up of 8111 adults in six U.S. cities.